Integrating Runtime Verification into an
Automated UAS Traffic Management System

Matthew Cauwels, Abigail Hammer, Benjamin Hertz, Phillip H. Jones, Kristin Y. Rozier

This webpage contains supplementary specifications for "Integrating Runtime Verification into an
Automated UAS Traffic Management System" by M. Cauwels, A. Hammer, B. Hertz, P. H. Jones, and K. Y. Rozier

SB_UTM_1

Specification Description

The waypoint latitude (wpLat) of any UAS's telemetry data will be bounded between MaxLatLB and MinLatUB.

Signals Required

wpLat

Boolean Conversion of Signals to Atomic Inputs

wpLat_leq_MaxLatUB = 1;
for(i = 0; i < NumUAS; i++)
{
    // if UAS i's wpLat is greater than the upper bounded
    // and the value is not "nan"
    if((wpLat[i] > MaxLatUB) && (wpLat[i] == wpLat[i])
    { 
        wpLat_leq_MaxLatUB = 0;
    }
} 
wpLat_geq_MinLatLB = 1;
for(i = 0; i < NumUAS; i++)
{
    // if UAS i's wpLat is less than the lower bounded
    // and the value is not "nan"
    if((wpLat[i] < MinLatLB) && (wpLat[i] == wpLat[i])
    { 
        wpLat_geq_MinLatLB = 0;
    }
}

MLTL Specification

Original: (wpLat_leq_MaxLatUB ∧ wpLat_geq_MinLatLB)

Updated: ☐[0,3] (wpLat_leq_MaxLatUB ∧ wpLat_geq_MinLatLB)

Fault Explanation

A UAS's waypoint latitude is not physically possible.

Additional Notes

Latitude can only ever by between -90 and 90 degrees. Anything outside these bounds is nonsensical and indicates a fault within the system.

Figures

Figure 1: All of the waypoint latitude (wpLat) inputs from each GCS the UTM reads from the telemetry datatable.
Figure 2: The output of R2U2's monitoring of specification SB_UTM_1, confirming that no UAS exceeds its waypoint latitude sensor bounds.
Figure 3: Since Fig. 1 had no wpLat inputs that exceeded MaxLatUB or MinLatLB, we manually injected a fault into a single UAS (purple).
Figure 4: The output of R2U2's monitoring of specification SB_UTM_1, showing that R2U2 catches when the injected fault occurs. However, notice that there is bouncing in the initial Boolean specificaiton, which can lead to undesireable false-positive alerts.
Figure 5: The output of R2U2's monitoring of the updated specification SB_UTM_1, showing that R2U2 catches when the injected fault occurs and the "☐[0,3]" temporal operator acts as a sliding filter, debouncing R2U2's output.